Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$112.46	5.329%	$118.453	$118.45	$118.45	$118.50
Purchase #2	$10.86	5.525%	$11.46	$11.46	$11.45	$11.50
Purchase #3	$237.85	10.819%	$263.583	$263.58	$263.60	$263.60
Purchase #4	$223.34	10.853%	$247.5791	$247.58	$247.60	$247.60
Purchase #5	$103.99	12.648%	$117.1427	$117.14	$117.15	$117.10
Purchase #6	$246.49	10.457%	$272.2655	$272.27	$272.25	$272.30
Purchase #7	$75.87	7.266%	$81.3827	$81.38	$81.40	$81.40
7 purchase totals =	$1,010.86		$1,111.8660	$1,111.86	$1,111.90	$1,112.00